This invention relates to a system for spray coating substrates such as a continuously moving web of plastic film with a coating material to form on drying a film on the substrate. For example, this invention is applicable to providing plastic materials such as polyethylene film used in the packaging industry with a coating of a copolymer of vinylidene chloride (commonly referred to as "PVDC") to provide the polyethylene film with a gas barrier coating to prevent the migration of gas such as air through the plastic film. The process provides initially a wet uniform coating on the substrate which coating is then dried completely coalescing the material into a polymer film.
In spray coating of such substrates, it is necessary to continuously deliver aqueous coating material to the spray nozzles for the coating of the substrate continuously passing through the spray coating booth and to control the airborne aqueous overspray to prevent its release to the atmosphere while containing the polymer particles, particularly without disturbing the liquid coating on the substrate or the spray pattern in the coating chamber.